Virtualization Interview Questions & Answers part2

QEMU is a generic and open source machine emulator and virtualizer. When used as a machine emulator, QEMU can run OS and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, Qemu achieves very good performance.

Q: – What is KVM (Kernel Virtual Machine )

KVM is a Linux kernel module that allows a user space program to utilize the hardware virtualization features of various processors.

Q: – Difference Between Qemu and KVM

QEMU

KVM

Qemu is a complete and standalone software ,it emulates the target operating system.

Qemu supports Para virtualization

To emulate more than just the processor, Qemu includes a long list of peripheral emulators: disk, network, VGA, PCI, USB, serial/parallel ports, etc.

KVM supports full virtualiztion

KVM is a fork of the Qemu executable ,Both teams work actively to keep difference at a minimum

Apart from the processor state switching, the kernel module also handles a few low-level parts of the emulation, like the MMU registers (used to handle VM) and some parts of the PCI emulated hardware.

Q: – Define snaphot of a virtual Machine ?

A snapshot is the state of a virtual machine and generally, its storage devices, at an exact point in time. Snapshots are taken by simply giving an order to do so at a given time, and can be “reverted” to on demand, with the effect that the VM appears exactly as it did when the snapshot was taken. Snaphot is useful as an extremely rapid backup technique, prior to a risky operation.

Storage virtualization, the process of completely abstracting logical storage from physical storage.Virtual disk drive, a computer program that emulates a disk drive such as a hard disk drive or optical disk drive in virtualized setup.

Q: – What is virtual Machine Cloning ?

Virtual Machine Cloning is a method of creating a copy of an existing virtual machine with the same configuration and installed software as the original.The existing virtual machine is called the parent of the clone. When the cloning operation is complete, the clone is a separate virtual machine.

Q: – What are the types of cloning in virtualization ?

A full clone is an independent copy of a virtual machine that shares nothing with the parent virtual machine after the cloning operation. Ongoing operation of a full clone is entirely separate from the parent virtual machine.

A linked clone is a copy of a virtual machine that shares virtual disks with the parent virtual machine in an ongoing manner. This conserves disk space, and allows multiple virtual machines to use the same software installation.